用液膜技术分离铌和钽

由煤油——仲辛醇——上胺体系组成的液膜技术分离铌(V)和钽(V),只要控制一定的料液相条件,就能快速,有效地分离。经一次处理能使含500ppm 的Ta_2 O_5几乎完全被萃取,而相同浓度的Nb_2 O_5其萃取率低于5%。     

直流电弧发射光谱法测定铌及铌合金中钽含量

采用直流电弧光谱仪对铌及铌合金中钽元素进行检测。通过试验确定满足分析条件的缓冲剂、样品与缓冲剂的配比及钽元素谱线并检测其精密度、准确度及检出限。结果表明,选择Li2CO3与碳粉1∶6混合作为缓冲剂,缓冲剂与样品比例为1∶2,钽元素的谱线为271.013 nm;加标回收率为94%~109%,测定值的相对标准偏差(测10次)均小于10%。     

钽铌工业生产及其展望

简述了钽、铌工业生产的新进展,重点介绍了钽、铌矿和钽、铌产品的生产技术进步和应用现状;分析了钽、铌产品的市场结构和价格走势,最后展望了钽、铌工业生产的未来发展.     

钽、铌专利研究

介绍了钽、铌专利文献的检索方案及通过专利方法确定钽、铌技术领域中核心技术的原则,并依据这些原则确定钽、铌技术领域中的核心技术.通过对钽、铌专利的研究,提出宁夏东方钽业股份有限公司应采取的对策.     

2007年钽铌工业发展评述

评述了2007年中国钽铌工业的运行状况.在世界钽铌产品总需求持续增长的带动下,中国钽铌工业继续保持良好的增长势头,工业生产总值达到22.79亿元,销售收入达到23.37亿元,分别比上年增长了27.9%和28.8%.2007年是中国钽铌工业快速发展的一年,矿产量和冶炼品产量增加,高端钽铌产品的加工和出口快速增长.最后分析了中国钽铌工业发展中存在的突出问题,并提出了促进行业发展的措施.     

钛阳极磁控溅射钽的工艺研究

涂层钛阳极在使用中会因氧化而失效.为了开发新型的涂层钛阳极,进行了磁控溅射钽作钛阳极底层的研究.通过改变溅射功率、氩气压力及溅射时间,对不同工艺条件下沉积的钽膜进行了分析.用XRD分析了溅射层的成分及相结构;通过SEM,AFM观察了钽膜的微观形貌和颗粒尺寸;用拉开法测定了钽膜的附着力.综合分析了影响钽膜质量的因素,推荐磁控溅射3～4靘钽膜的优化工艺为:功率100～130 W,氩气压力0.1～0.3 Pa,溅射时间45～50 min.钽膜作为底层可提高二氧化铅阳极的使用寿命40倍以上.     

2006年中国钽铌工业发展述评

评述了2006年中国钽铌工业的运行状况.在世界钽铌产品总需求持续增长的带动下,中国钽铌工业也呈现出良好的增长势头,总产值达到17.82亿元,销售收入达到18.15亿元,与2005年相比分别增长了23.58%和20%.中国电容器用钽粉和钽丝的质量已接近国际先进水平,产量已分别占世界产量的21%和56%以上,出口总量达到总产量的90%以上.最后分析了中国钽铌工业发展中存在的突出问题,并提出了促进行业发展的措施.     

钽铌资源及中国钽铌工业的发展

详细综述了国内外钽铌资源的储量、特点、品位和分布及世界钽铌产品的结构、消耗数量及应用领域.着重介绍了我国钽铌在采矿、选矿、冶金和钽铌金属加工方面的技术进步和创新.最后作者对我国钽铌事业的发展提出了建设性的意见.     

铌、钽电容器性能分析

钽铌属于同族元素 都是阀金属材料,其介电常数分别为27、41,都可以用来制作电解电容器。本文使用铌和钽2种材料分别制作电解电容器,并通过容量损耗测试仪、漏电流测试仪、电子扫描电镜等分析仪器对其和始性能、偏压性能、温度特性、寿命特性及其电介质层的微观特性进行检测分析。结果表明使用铌材料同样可以得到性能较好的电解电容器。     

中国钽铌工业的进步与展望

文章简要地回顾了九○五厂钽铌工业发展历程，并与世界钽铌工业作了对比分析。以详实的资料和基础数据，清晰地描述了我国钽铌工业发展现状和技术发展历程及其在世界钽铌工业发展中所处的地位和竞争能力；充分阐明了我国稀有金属钽铌资源及其在冶炼、加工技术领域中所存在的问题和面临的形势。从国家安全角度及行业整体发展的高度，提出了对国内稀有金属钽铌行业进行重组整合和积极开发国外资源的可持续发展的战略构想。     

Production and superconducting properties of laboratory scale NbTi and NbTiTa multifilamentary cables

A comparison of high field, low temperature superconducting properties between a Nb47^w/o Ti and two NbTiTa alloys as bases of laboratory scale cables was carried out Optimization cycles needed to obtain fair superconducting properties imply intermediate thermal treatments in the range 380–400°C during deformation at cold-work of 70%. The ternary alloys exhibit excellent ductile properties as do NbTi alloys. After an adequate optimization cycle the alloy Nb38^w/o Ti34^w/o Ta showed the best high field superconducting properties with values of more than 600 A mm^?2 at 12 Tesla and 2.15 K.     

球形Ta2O5/Nb2O5制备方法的研究

研究了用氨沉淀氟钽(或铌)酸溶液制备球形Ta2O5/Na2O5工艺.通过实验探讨了沉淀条件、溶液浓度、沉淀时间、焙烧温度等工艺参数的最佳组合.结果表明,用氨沉淀氟钽(或铌)酸溶液制备球形的Ta2O5/Nb2O5,必须首先得到不规则的Ta(OH)5/Nb(OH)5.要得到不规则Ta(OH)5/Nb(OH)5,反应时搅拌强度要大,搅拌速率应控制在800～1 200 r/min,反应结束后继续搅拌10～20 min,终点pH值控制为8.5;氟钽(或铌)酸溶液浓度为60～80 g/L沉淀10 min,浓度为120～140 g/L沉淀15 min,之后可得到不规则Ta(OH)5/Nb(OH)5.再在800～850℃,焙烧6 h可得到球形Ta2O5/Nb2O5.     

Intra-granular alpha precipitation in Ti–Nb–Zr–Ta biomedical alloys

This article investigates the intra-granular precipitation of nanometer-scale α platelets in the β matrix of a complex quaternary β titanium alloy, Ti-35Nb-7Zr-5Ta (all in wt%), for orthopedic implant applications, during β-solutionizing/quenching/aging type heat-treatments. The role of metastable ω precipitates on the nucleation and growth of these α precipitates, has been specifically addressed by coupling transmission electron microscopy (TEM) and 3D atom probe (3DAP) tomography studies on this alloy. Athermal ω precipitates form in this alloy on quenching from above the β-transus temperature. On isothermal annealing at low temperatures (~400 °C), these ω precipitates coarsen, rejecting Zr into the adjacent β matrix as determined by 3DAP studies. Concurrently, the nucleation and growth of α precipitates is initiated at or near the ω/β interfaces, as determined by TEM studies. In addition to coherency strains induced by the ω precipitates, the local enrichment of Zr adjacent to these precipitates appears to play an important role in aiding the nucleation and growth of Zr-rich α precipitates in this alloy.     

Nb、Ti、Ta扩散行为对NbTiTa超导线材制备的影响

研究了经过1000℃/10 h热处理的Nb/Ti、Nb/Ta、Ti/Ta扩散偶样品所形成合金层的成分分布,以及Ti/Ta扩散偶经过850℃、700℃、550℃、400℃5 h热处理后淬火与随炉冷却形成的TiTa合金微观组织的区别,并研究了复合体中Nb片、Ti片、Ta的排列方式对NbTiTa超导线材微观结构和扩散工艺的影响.     

Electromagnetic wave absorbing properties of TMCs (TM=Ti,Zr, Hf,Nb and Ta) and high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C

Electromagnetic wave (EMW) absorbing materials play a vital role in modern communication and information processing technologies to inhibit information leakage and prevent possible damages to environment and human bodies.Currently,most of EMW absorbing materials are either composites of two or more phases or in the form of nanosheets,nanowires or nanofibers in order to enhance the EMW absorption performance through dielectric loss,magnetic loss and dielectric/magnetic loss coupling.However,the combination of complex shapes/multi phases and nanosizes may compound the difficulties of materials processing,composition and interfaces control as well as performance maintenance during service.Thus,searching for single phase materials with good stability and superior EMW absorbing properties is appealing.To achieve this goal,the EMW absorbing properties of transition metal carbides TMCs (TM=Ti,Zr,Hf,Nb and Ta) and high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C which belong to ultrahigh temperature ceramics,were investigated in this work.Due to the good electrical conductivity and splitting ofd orbitals into lower energy t2g level and higher energy eg level in TMC6 octahedral arrangement,TMCs (TM=Ti,Zr,Hf,Nb and Ta) exhibit good EMW absorbing properties.Especially,HfC and TaC exhibit superior EMW absorbing properties.The minimum reflection loss (RLmin) value of HfC is -55.8 dB at 6.0 GHz with the thickness of 3.8 mm and the effective absorption bandwidth (EAB) is 6.0 GHz from 12.0 to 18.0 GHz at thickness of 1.9 mm;the RLmin value of TaC reaches-41.1 dB at 16.2 GHz with a thickness of 2.0 mm and the EAB is 6.1 GHz with a thickness of 2.2 mm.Intriguingly,the electromagnetic parameters,i.e.,complex permittivity and permeability are tunable by forming single phase solid solution or high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C.The RLmin value of high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C is -38.5 dB at 9.5 GHz with the thickness of 1.9 mm,and the EAB is 2.3 GHz (from 11.3 to 13.6 GHz) atthickness of 1.5 mm.The significance of this work is that it opens a new window to design single phase high performance EMW absorbing materials by dielectric/magnetic loss coupling through tuning the conductivity and crystal field splitting energy of d orbitals of transition metals in carbides,nitrides and possibly borides.     

Ambient temperature formation of (Ta,Nb)C and (Ta,Nb)N

A tantalum/niobium concentrate has been mechanically milled with magnesium and either graphite or nitrogen for 100 h. Directly after milling the formation of MgO was evident in both systems, a mixed metal carbide (Ta,Nb)C was also present in the carbon system. A cubic phase, close to that expected for the mixed metal nitride, was found in the powder milled under nitrogen. Annealing of the powders showed the reaction was incomplete with reduced oxide phases present. The carbide/nitride phases were readily separated from the MgO by acid leaching which left powders <5 m in size. The leaching preferentially dissolved the smaller, more highly strained crystallites in both cases.     

The influence of chemical composition and thermo-mechanical treatment on Ti–Nb–Ta–Zr alloys

Ti–Nb–Ta–Zr quaternary alloying system is very promising for biomedical alloys. It is due to good mechanical properties and corrosion resistance of titanium alloys. Moreover no potentially harmful elements are contained in this system.Mechanical properties were influenced by changing the chemical composition and by various heat-treatment operations. The alloys were prepared by arc melting and then they were hot forged (900–1000 °C). After solution treatment 850 °C/0.5 h/water quenched, cold swaging was carried out with section reduction about 85%. As final heat treatment aging at 450 °C/8 h/furnace cooling was used.Mechanical properties were measured from tensile tests results at cold swaged and aged specimens. The microstructure was observed by using light microscopy and transmission electron microscopy (TEM)-thin foils method. X-ray diffraction analysis reveals the phase composition. By using these techniques the changes in microstructure caused by precipitation during aging treatment were clarified. After aging, the presence of ω or α phases may occur. Influence of changing Zr and Ta contents on mechanical properties and also on precipitation of secondary phases during aging treatment was observed.     

Effect of Ta content on mechanical properties of Ti–30Nb–XTa–5Zr

In this study, we investigated the effect of Ta content on the mechanical properties of Ti–30Nb–XTa–5Zr fabricated by a powder metallurgy method, for biomedical applications. The Ta content ranged from 0% to 20 mass%.The microstructures of Ti–30Nb–XTa–5Zr that contain less than 5 mass% Ta comprise β phase and an ω phase. The tensile properties of Ti–30Nb–XTa–5Zr change with a change in their deformation mechanisms. The deformation mechanisms of Ti–30Nb–XTa–5Zr, which contains less than 10 mass% Ta, is the stress-induced martensite (SIM) transformation, while that of Ti–30Nb–XTa–5Zr, which contains over 20 mass% Ta, is the slip mechanism. The minimum elastic modulus is obtained in Ti–30Nb–10Ta–5Zr, which comprises a single β phase.     

Relationships between tensile deformation behavior and microstructure in Ti–Nb–Ta–Zr system alloys

Ti–Nb–Ta–Zr system alloys are receiving more attention for biomedical material component applications. However, the deformation behavior of the Ti–Nb–Ta–Zr system has not been evaluated to date. Therefore, the deformation behavior of Ti–Nb–Ta–Zr alloys with different Nb contents was investigated in this study.The behaviors of loading–unloading stress–strain curves of Ti–20Nb–10Ta–5Zr and Ti–25Nb–10Ta–5Zr air-cooled after final heating of the manufacturing process are similar to that obtained in metastable β type titanium alloys that have the shape memory effect. Therefore, the shape memory effect was expected in Ti–20Nb–10Ta–5Zr and Ti–25Nb–10Ta–5Zr alloys. The elastic deformation of Ti–30Nb–10Ta–5Zr disobeyed Hooke's law. However, stress or strain-induced martensite (SIM) is not observed on the loading–unloading stress–strain curve. The deformation mechanism of Ti–25Nb–10Ta–5Zr changes with varying its microstructure. In Ti–25Nb–10Ta–5Zr air-cooled after final heating, the microstructure consisted of an ω phase in a β phase. The stress for inducing martensite in a β phase, σ_M, was nearly equal to the yielding stress, σ_y. Therefore, stress-induced martensitic transformation and movement of dislocations occurred together. In Ti–25Nb–10Ta–5Zr water-quenched after final heating of the manufacturing process, the microstructure consisted of a single β phase, where σ_M is lower than σ_y. Therefore, stress-induced martensitic transformation occurred before yielding.